LRFD COMBINATIONS Egyptian code for loads on buildings and structures سلسلة شرح الكود المصرى للأحمال على المبانى و المنشأت هنتعرف مع بعض على طريقة LRFD و مميزات استخدامها و هنقارنها مع طريقة ASD Ultimate combinations Load resistance factored design method advantages of LRFD factors for loads factors for strength Youtube :-https://www.youtube.com/channel/UCRmQWyw1F1cnD_XvoBhgv1Q/featured FaceBook Page:-https://www.facebook.com/Advanced-Structures-Smart-Engineers-100680119286424/?notif_id=1649169062355891&notif_t=page_user_activity&ref=notif Linked In:- https://www.linkedin.com/in/mohamed-ismail-fe-civil-07667478/

1. ECP-201
Egyptian Code for Loads
Prepared By
Eng: Mohamed Ismail Kotb
Email: m.ismailkotb@gmial.com
Tel: 01121549164
Eng. Mohamed Ismail Kotb

2. CODE Chapters
Chapter 1
Overview
Chapter 2
Definitions
Chapters 3 & 4
Loads on Buildings
Dead Loads
ch-3
Live Loads
ch-4
Chapters 5 & 6
Loads on Bridges
Roadway
Bridges
Ch-5
Railway
Bridges
Ch-6
Chapter 7
Wind Loads
Chapters 8, 9 & 10
Seismic Loads
Buildings
Ch-8
Bridges
Ch-9
Tanks
Ch-10
Eng. Mohamed Ismail Kotb

3. Eng. Mohamed Ismail Kotb

4. Chapter(2) Outlines
Definitions of Loads
Load Combinations Concepts
Load Combinations (ASD & LRFD)
LRFD Method
Resistance Concepts in LRFD
Reliability and LRFD Specification
Eng. Mohamed Ismail Kotb

5. Chapter(2) LRFD Method
 General Equation for LRFD Method
All the computation for factored resistance and factored load shall be in accordance with the following equation.
ø: resistance factor
∅ 𝑹𝒏 ≥ ෍ ∝𝒊 𝑸𝒊
Qi: Load effect
Rn: Nominal resistance α: Load factors
Pu: Factored Load
Increase in Load effect ≥ 1
Pu=1.2 PDL +1.6 PLL
Pu
PD
PD: Factored Design Strength
Reduction in strength <1
PD= ø Pn =0.9 Pn
Eng. Mohamed Ismail Kotb

6. Chapter (2) Resistance Concepts
Eng. Mohamed Ismail Kotb

7. (LRFD) method
 1- LRFD provides a flexibility options for the designers.
‫للمقاومة‬ ‫أخرى‬ ‫و‬ ‫لألحمال‬ ‫معامالت‬ ‫لوجود‬ ‫نظرا‬ ‫لتصميم‬ ‫في‬ ‫مرونة‬ ‫تعطى‬
 2- Using multiple load factor combinations should lead to economy and more reliable.
‫أوفر‬ ‫يكون‬ ‫أكثرو‬ ‫مصداقية‬ ‫يعطى‬ ‫األحمال‬ ‫من‬ ‫نوع‬ ‫لكل‬ ‫مختلفة‬ ‫معامالت‬ ‫وجود‬
 3- Change in resistance factor "ø" are much easier to make than (ASD)
‫في‬ ‫المقاومة‬ ‫معامل‬
LRFD
‫من‬ ‫أكثر‬ ‫بسهولة‬ ‫تغييره‬ ‫يمكن‬
ASD
 4- LRFD makes design in all materials more compatible and can be used for any material.
‫الطريقة‬ ‫هذه‬ ‫استخدام‬ ‫يمكن‬
‫فى‬
‫عن‬ ‫مختلفة‬ ‫األحمال‬ ‫معامالت‬ ‫ألن‬ ‫المختلفة‬ ‫المواد‬ ‫من‬ ‫نوع‬ ‫أي‬ ‫تصميم‬
‫المواد‬ ‫مقاومة‬ ‫معامالت‬
 5- Gives safer structures because this method lead to a better awareness of structural behavior
‫أمانا‬ ‫أكثر‬ ‫تصميم‬ ‫تعطى‬
‫للمنشأت‬
‫المنشأ‬ ‫لسلوك‬ ‫أكثر‬ ‫معرفة‬ ‫تعطى‬ ‫ألنها‬
‫األحمال‬ ‫من‬ ‫القصوى‬ ‫المرحلة‬ ‫في‬
 6- For low live load to dead ratio, this method is economic.
‫الدائمة‬ ‫إلى‬ ‫الحية‬ ‫األحمال‬ ‫بين‬ ‫متقاربة‬ ‫النسبة‬ ‫تكون‬ ‫عندما‬ ‫أكثر‬ ‫اقتصادية‬ ‫الطريقة‬ ‫هذه‬ ‫تكون‬
Eng. Mohamed Ismail Kotb

8. Chapter(2) LRFD Method
 Comparison of (LRFD) with (ASD) for tension members:
 Using (LRFD):
Actual force (1.2 D + 1.6 L) or (1.4 D)
Allowable stresses 0.85 Fy
 Using (ASD):
Actual force L + D
Allowable stresses 0.58 Fy
 From the curve, it is clear that LRFD is
More economic for L/D less than 2,
 while ASD is more economic,
if L/D more than 2.
Eng. Mohamed Ismail Kotb